Enhancing biological stability of disinfectant-free drinking water by reducing high molecular weight organic compounds with ultrafiltration posttreatment.

The production of biologically stable drinking water is challenging in conventional surface water treatment plants. However, attainment of biological stability is essential to avoid regrowth in disinfectant-free distribution systems. A novel application of ultrafiltration as a posttreatment step to enhance biological stability of drinking water produced in an existing conventional surface water treatment plant was investigated. The conventional full-scale plant comprised coagulation/sedimentation/filtration, UV-disinfection, biological activated carbon filtration and chlorine dioxide post-disinfection. The produced water exhibited substantial regrowth of Aeromonads, invertebrates and colony counts in the distribution network. Recent literature attributes this phenomenon to the specific presence of slowly biodegradable, high molecular weight (MW) biopolymeric organic compounds. Hence, the aim of this study is to enhance the biological stability of conventionally treated surface water by reducing the concentration of high-MW organic compounds. For this purpose, biological active carbon filtrate was subjected to ultrafiltration with membrane pore sizes of 10 kDa, 150 kDa and 0.12 µm respectively, operating in parallel. The UF performance was evaluated in terms of the achieved reduction in particulate and high-MW organic carbon (PHMOC); the biopolymer fraction in Liquid Chromatography-Organic Carbon Detection; biomass (cells, ATP); Assimilable Organic Carbon (AOC) by the AOC-P17/NOX method for easily biodegradable, low-MW compounds and by the AOC-A3 method for slowly biodegradable, high-MW compounds; and overall microbial growth potential (MGP) as assessed by Biomass Production Potential (BPP) and Bacterial Growth Potential (BGP) bio-assays. Results showed increasing removal of high-MW organic carbon with decreasing UF pore size, i.e., 30%, 60% and 70% removal was observed for the 0.12 µm, 150 kDa and 10 kDa membranes, respectively. Biomass and particulates retention was more than 95% for all UF membranes. AOC-A3, BPP and BGP were substantially reduced by 90%, 70% and 50%, respectively. These respective reductions were similar for all three UF membranes despite their difference in pore size. Easily biodegradable organic compounds (as AOC-P17/NOX) were not reduced by any of the membranes, which was in accordance with expectations considering the low MW of the compounds involved. Based on the obtained results, growth potential appears to be largely attributable to high-MW organic compounds which are retained by a 0.12 µm UF membrane. Furthermore, the quality of all three UF permeates was equal to or better than in reference cases (literature data) which exhibit little regrowth in their disinfectant-free distribution networks. The results demonstrate that ultrafiltration posttreatment in conventional surface water treatment plants is a potentially promising approach to enhance the biological stability of drinking water.

The support needs of parents having a child with a chronic kidney disease: a focus group study.

BACKGROUND: Parents of children with a chronic kidney disease (CKD) have a crucial role in the management of their child's disease. The burden on parents is high: they are often exhausted, depressed and experience high levels of stress and a low quality of life, which could have a negative impact on their child's health outcomes. Support aiming at preventing and reducing parental stress is essential. Therefore, it is necessary to have insight in the problems and support needs among these parents. OBJECTIVE: Our aim is to describe parents' support needs regarding the problems they experience in having a child with CKD. METHODS: Five focus group interviews were conducted with parents of children: (i) with hereditary kidney disease, (ii) with nephrotic syndrome, (iii) with chronic kidney failure, (iv) using dialysis and (v) after renal transplantation. The children were treated at a paediatric nephrology unit in one university hospital in the Netherlands. The data were thematically analysed. RESULTS: Twenty-one parents participated in the focus groups. Parents need more information about their child's CKD and treatment options, and managing their own hobbies and work. Furthermore, parents need emotional support from their partner, family, friends, peers and healthcare professionals to help them cope with the disease of their child. Additionally, parents need practical support to hand over their care and support in transport, financial management and regarding their child at school. CONCLUSION: Needs regarding balancing their personal life are seldom prioritized by parents as the child's needs are considered more important. Therefore, it is important that healthcare professionals should not only attend to the abilities of parents concerning their child's disease management, but also focus on the parents' abilities in balancing their responsibilities as a caregiver with their own personal life.

TRPV1 dysfunction in cystinosis patients harboring the homozygous 57 kb deletion.

Cystinosis is a rare autosomal recessive disorder characterized by lysosomal cystine accumulation due to loss of function of the lysosomal cystine transporter (CTNS). The most common mutation in cystinosis patients of Northern Europe consists of a 57-kb deletion. This deletion not only inactivates the CTNS gene but also extends into the non-coding region upstream of the start codon of the TRPV1 gene, encoding the capsaicin- and heat-sensitive ion channel TRPV1. To evaluate the consequences of the 57-kb deletion on functional TRPV1 expression, we compared thermal, mechanical and chemical sensitivity of cystinosis patients with matched healthy controls. Whereas patients heterozygous for the 57-kb deletion showed normal sensory responses, homozygous subjects exhibited a 60% reduction in vasodilation and pain evoked by capsaicin, as well as an increase in heat detection threshold. Responses to cold, mechanical stimuli or cinnamaldehyde, an agonist of the related nociceptor channel TRPA1, were unaltered. We conclude that cystinosis patients homozygous for the 57-kb deletion exhibit a strong reduction of TRPV1 function, leading to sensory deficiencies akin to the phenotype of TRPV1-deficient mice. These deficits may account for the reported sensory alterations and thermoregulatory deficits in these patients, and provide a paradigm for life-long TRPV1 deficiency in humans.

Late Stone Age human remains from Ishango (Democratic Republic of Congo): New insights on Late Pleistocene modern human diversity in Africa.

Although questions of modern human origins and dispersal are subject to intense research within and outside Africa, the processes of modern human diversification during the Late Pleistocene are most often discussed within the context of recent human genetic data. This situation is due largely to the dearth of human fossil remains dating to the final Pleistocene in Africa and their almost total absence from West and Central Africa, thus limiting our perception of modern human diversification within Africa before the Holocene. Here, we present a morphometric comparative analysis of the earliest Late Pleistocene modern human remains from the Central African site of Ishango in the Democratic Republic of Congo. The early Late Stone Age layer (eLSA) of this site, dated to the Last Glacial Maximum (25-20 Ky), contains more than one hundred fragmentary human remains. The exceptional associated archaeological context suggests these remains derived from a community of hunter-fisher-gatherers exhibiting complex social and cognitive behaviors including substantial reliance on aquatic resources, development of fishing technology, possible mathematical notations and repetitive use of space, likely on a seasonal basis. Comparisons with large samples of Late Pleistocene and early Holocene modern human fossils from Africa and Eurasia show that the Ishango human remains exhibit distinctive characteristics and a higher phenotypic diversity in contrast to recent African populations. In many aspects, as is true for the inner ear conformation, these eLSA human remains have more affinities with Middle to early Late Pleistocene fossils worldwide than with extant local African populations. In addition, cross-sectional geometric properties of the long bones are consistent with archaeological evidence suggesting reduced terrestrial mobility resulting from greater investment in and use of aquatic resources. Our results on the Ishango human remains provide insights into past African modern human diversity and adaptation that are consistent with genetic theories about the deep sub-structure of Late Pleistocene African populations and their complex evolutionary history of isolation and diversification.

Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment.

Carnitine Profile and Effect of Suppletion in Children with Renal Fanconi Syndrome due to Cystinosis.

BACKGROUND: Cystinosis is an autosomal recessive disorder marked by intralysosomal cystine accumulation. Patients present with generalized proximal tubular dysfunction called renal Fanconi syndrome. Urinary carnitine loss results in plasma and muscle carnitine deficiency, but no clinical signs of carnitine deficiency have been described. Also, the optimal dose of carnitine supplementation is undefined. This study aimed to determine whether currently recommended carnitine doses result in adequate correction of plasma carnitine. METHODS: Five cystinosis patients with renal Fanconi syndrome, aged 2-18 years, were included. L-carnitine was prescribed 50 mg/kg/day since diagnosis: median 36 (range 18-207) months. Total and free plasma and urine carnitine and carnitine profiles were measured at study onset, after stopping L-carnitine for 3 months and 3 months after reintroducing L-carnitine 50 mg/kg/day. RESULTS: At study onset, plasma free carnitine was normal in all patients, total carnitine (1/5), acetylcarnitine (3/5), and several short- and medium-chain acylcarnitines ≤10 carbons (5/5) were increased indicating carnitine over-supplementation. Three months after cessation, carnitine profiles normalized and 3/5 patients showed plasma carnitine deficiency. Three months after reintroduction, plasma free carnitine normalized in all patients, however, carnitine profiles were disturbed in 4/5 patients. Urine free carnitine, acetylcarnitine, and acylcarnitines ≤10 carbons were increased in all patients independent of carnitine supplementation. CONCLUSION: Administration of recommended doses L-carnitine (50 mg/kg/day) resulted in over-supplementation. Although the drug is considered to be rather safe, long-term effects of over-supplementation remain unknown warranting cautious use of high doses. Plasma carnitine profile might be used as a monitor, to prevent overdosing.

Forward osmosis for application in wastewater treatment: a review.

Research in the field of Forward Osmosis (FO) membrane technology has grown significantly over the last 10 years, but its application in the scope of wastewater treatment has been slower. Drinking water is becoming an increasingly marginal resource. Substituting drinking water for alternate water sources, specifically for use in industrial processes, may alleviate the global water stress. FO has the potential to sustainably treat wastewater sources and produce high quality water. FO relies on the osmotic pressure difference across the membrane to extract clean water from the feed, however the FO step is still mostly perceived as a "pre-treatment" process. To prompt FO-wastewater feasibility, the focus lies with new membrane developments, draw solutions to enhance wastewater treatment and energy recovery, and operating conditions. Optimisation of these parameters are essential to mitigate fouling, decrease concentration polarisation and increase FO performance; issues all closely related to one another. This review attempts to define the steps still required for FO to reach full-scale potential in wastewater treatment and water reclamation by discussing current novelties, bottlenecks and future perspectives of FO technology in the wastewater sector.

Sorption and biodegradation of organic micropollutants during river bank filtration: a laboratory column study.

This study investigated sorption and biodegradation behaviour of 14 organic micropollutants (OMP) in soil columns representative of the first metre (oxic conditions) of the river bank filtration (RBF) process. Breakthrough curves were modelled to differentiate between OMP sorption and biodegradation. The main objective of this study was to investigate if the OMP biodegradation rate could be related to the physico-chemical properties (charge, hydrophobicity and molecular weight) or functional groups of the OMPs. Although trends were observed between charge or hydrophobicity and the biodegradation rate for charged compounds, a statistically significant linear relationship for the complete OMP mixture could not be obtained using these physico-chemical properties. However, a statistically significant relationship was obtained between biological degradation rates and the OMP functional groups. The presence of ethers and carbonyl groups will increase biodegradability, while the presence of amines, ring structures, aliphatic ethers and sulphur will decrease biodegradability. This predictive model based on functional groups can be used by drinking water companies to make a first estimate whether a newly detected compound will be biodegraded during the first metre of RBF or that additional treatment is required. In addition, the influence of active and inactive biomass (biosorption), sand grains and the water matrix on OMP sorption was found to be negligible under the conditions investigated in this study. Retardation factors for most compounds were close to 1, indicating mobile behaviour of these compounds during soil passage. Adaptation of the biomass towards the dosed OMPs was not observed for a 6 month period, implying that new developed RBF sites might not be able to biodegrade compounds such as atrazine and sulfamethoxazole in the first few months of operation.

The CERTAIN Registry: a novel, web-based registry and research platform for pediatric renal transplantation in Europe.

BACKGROUND: The results of pediatric renal transplantation have improved markedly in the last decade. However, a number of relevant clinical problems remain, such as organ damage caused by chronic rejection, long-term toxicity of immunosuppressive therapy, difficulty in developing tolerance-inducing protocols, secondary cardiovascular comorbidity, post-transplantation lymphoproliferative disease, suboptimal longitudinal growth, quality of life, adherence to immunosuppressive medication, and structured transition programs to adult care. These unmet clinical needs require intense collaborative and interdisciplinary clinical research. We recently founded the Cooperative European Paediatric Renal TransplAnt INitiative (CERTAIN; www.certain-registry.eu) as a research network and platform built on a novel, web-based registry. RESULTS: The registry's dataset provides essential information on generic kidney transplantation-related topics and also captures pediatric-specific topics, such as growth, physical and psychosocial development, and adherence. Due to its flexibility the system can be used as follows: (1) as a registry capturing a minimal or an extended dataset; (2) as a center and/or country-specific transplantation database; or (3) as a patient-specific electronic transplantation chart. The data can be exported directly from the CERTAIN web application into statistical software packages for scientific analyses. The rights regarding data ownership, evaluation, and publications are regulated in the registry's rules of procedure. Data quality is ensured by automatic software validation and a manual data review process. To avoid redundant data entry, CERTAIN has established interfaces for data change with Eurotransplant, the Collaborative Transplant Study (CTS), and the registry of the European Society of Pediatric Nephrology (ESPN) and European Renal Association - European Dialysis and Transplant Association (ERA-EDTA) (ESPN/ERA-EDTA registry). CERTAIN fulfils all regulatory and ethical requirements of the European Union and Germany, in particular, regarding patients' data privacy and security. CONCLUSION: Using modern information technology, the recently established multinational CERTAIN Registry fills a gap in Europe for collaborative 5 research and quality assurance in the field of pediatric renal transplantation.

Quantitative assessment of the efficacy of spiral-wound membrane cleaning procedures to remove biofilms.

Cleaning of high pressure RO/NF membranes is an important operational tool to control biofouling. Quantitative information on the efficacy of cleaning agents and protocols to remove biomass is scarce. Therefore, a laboratory cleaning test to assess the efficiency of cleaning procedures to remove attached biomass was developed. The major components of the test are (i) production of uniform biofilm samples, (ii) the quantification of the biomass concentrations with robust parameters and (iii) a simple test procedure with optimal exposure of the biofilm samples to the chemicals. The results showed that PVC-P is a suitable substratum for the production of uniform biofilm samples. ATP and carbohydrates (CH) as major components of the biofilm matrix for nucleotides (living bacterial cells) and extracellular polymeric substances EPS, respectively, were selected as robust biomass parameters. The removal of ATP and CH with the NaOH/Sodium Dodecyl Sulfate (SDS) mixture, selected as a standard treatment at pH 12.0, was reproducible. The resistance of the EPS matrix against chemical cleaning was demonstrated by a low CH removal (32.8 ± 6.0%) compared to the ATP removal (70.5 ± 15.1%). The inverse relationship of biomass removal with the CH to ATP ratio (µg/ng) of the biofilms demonstrated the influence of the biomass characteristics on cleaning. None of the 27 chemicals tested (analytical-grade and commercial brands) in single step or in double-step treatments were significantly more effective than NaOH/SDS. Oxidizing agents NaOCl and H(2)O(2), the latter in combination with SDS, both tested as common agents in biofilm control, showed a significantly higher efficiency (70%) to remove biofilms. In the test, simultaneously, the efficiency of agents to remove precipitated minerals such as Fe can be assessed. Validation tests with Cleaning in Place (CIP) in 8 and 2.5-inch RO membrane pilot plant experiments showed similar ranking of the cleaning efficiency of cleaning protocols as determined in the laboratory tests. Further studies with the laboratory test are required to study the effect of cleaning conditions such as duration, temperature, shear forces as well as chemical conditions (concentrations, alternative agents or mixtures and sequence of application) on the efficiency to remove attached biomass.

Neonatal onset autosomal dominant polycystic kidney disease (ADPKD) in a patient homozygous for a PKD2 missense mutation due to uniparental disomy.

Autosomal dominant polycystic kidney disease (ADPKD), due to a heterozygous mutation in PKD1 or PKD2, is usually an adult onset disease. Renal cystic disease is generally milder in PKD2 patients than in PKD1 patients. Recently, several PKD1 patients with a severe renal cystic phenotype due to a second modifying PKD1 allele, or carrying two incomplete penetrant PKD1 alleles, have been described. This study reports for the first time a patient with neonatal onset of PKD homozygous for an incomplete penetrant PKD2 missense variant due to uniparental disomy.

The innovative osmotic membrane bioreactor (OMBR) for reuse of wastewater.

An innovative osmotic membrane bioreactor (OMBR) is currently under development for the reclamation of wastewater, which combines activated sludge treatment and forward osmosis (FO) membrane separation with a RO post-treatment. The research focus is FO membrane fouling and performance using different activated sludge investigated both at laboratory scale (membrane area of 112cm2) and at on-site bench scale (flat sheet membrane area of 0.1 m2). FO performance on laboratory-scale (i) increased with temperature due to a decrease in viscosity and (ii) was independent of the type of activated sludge. Draw solution leakage increased with temperature and varied for different activated sludge. FO performance on bench-scale (i) increased with osmotic driving force, (ii) depended on the membrane orientation due to internal concentration polarization and (iii) was invariant to feed flow decrease and air injection at the feed and draw side. Draw solution leakage could not be evaluated on bench-scale due to experimental limitation. Membrane fouling was not found on laboratory scale and bench-scale, however, partially reversible fouling was found on laboratory scale for FO membranes facing the draw solution. Economic assessment indicated a minimum flux of 15L.m-2 h-1 at 0.5M NaCl for OMBR-RO to be cost effective, depending on the FO membrane price.

Renal transplantation for fibromuscular dysplasia.

This is the first report that presents renal transplantation after bilateral nephrectomy as the final treatment for severe renovascular hypertension due to fibromuscular dysplasia (FMD). We describe the history of a 1-year-old girl who suffered from renovascular hypertension due to FMD. Imaging revealed multiple bilateral stenoses of the renal artery extending into the distal branches. The hypertension proved unresponsive to pharmacologic treatment and the intrarenal peripherally located stenoses rendered a conventional approach such as transluminal or surgical angioplasty not feasible. At the age of 5 years, a unilateral nephrectomy of the most affected kidney was performed, but she remained hypertensive and developed progressive cardiomyopathy and retinopathy. At the age of 6 years the remaining kidney was removed, followed by a living related renal transplantation with a kidney donated by her mother. Posttransplantation, she developed mild hypertension due to a postanastomotic stenosis, which was easily controlled with antihypertensives. Now 8 years after transplantation, she has experienced no further blood pressure related problems. Although there is a risk of recurrence of FMD after performing a living related transplantation, our report suggests that this procedure is relatively safe, provided appropriate preoperative evaluation and follow up is performed.

Threshold concentrations of biomass and iron for pressure drop increase in spiral-wound membrane elements.

In a model feed channel for spiral-wound membranes the quantitative relationship of biomass and iron accumulation with pressure drop development was assessed. Biofouling was stimulated by the use of tap water enriched with acetate at a range of concentrations (1-1000 µgCl(-1)). Autopsies were performed to quantify biomass concentrations in the fouled feed channel at a range of Normalized Pressure Drop increase values (NPD(i)). Active biomass was determined with adenosinetriphosphate (ATP) and the concentration of bacterial cells with Total Direct Cell count (TDC). Carbohydrates (CH) were measured to include accumulated extracellular polymeric substances (EPS). The paired ATP and CH concentrations in the biofilm samples were significantly (p<0.001; R(2)=0.62) correlated and both parameters were also significantly correlated with NPD(i) (p<0.001). TDC was not correlated with the pressure drop in this study. The threshold concentration for an NPD(i) of 100% was 3.7 ng ATP cm(-2) and for CH 8.1 µg CH cm(-2). Both parameters are recommended for diagnostic membrane autopsy studies. Iron concentrations of 100-400 mg m(-2) accumulated in the biofilm by adsorption were not correlated with the observed NPD(i), thus indicating a minor role of Fe particulates at these concentrations in fouling of spiral-wound membrane.

Neurocognitive functioning in school-aged cystinosis patients.

INTRODUCTION: Cystinosis is an autosomal recessive disorder leading to intralysosomal cystine accumulation in various tissues. It causes renal Fanconi syndrome and end stage renal failure around the age of 10 years if not treated with cysteamine. Children with cystinosis seem to have a normal intelligence but frequently show learning difficulties. These problems may be due to specific neurocognitive deficits rather than impaired renal function. Whether cysteamine treatment can improve cognitive functioning of cystinosis patients is thus far unknown. We aim to analyze neurocognitive functioning of school-aged cystinosis patients treated with cysteamine in order to identify specific deficits that can lead to learning difficulties. PATIENTS AND METHODS: Fourteen Dutch and Belgian school-aged cystinosis patients were included. Glomerular filtration rate was estimated using the Schwartz formula. Children were tested for general intelligence, visual-motor integration, inhibition, interference, sustained attention, accuracy, planning, visual memory, processing speed, motor planning, fluency and speed, and behavioural and emotional functioning using standardized methods. RESULTS: Glomerular filtration rate ranged from 22 to 120 ml min(-1) 1.73 m(-2). Median full-scale intelligence was below the average of a normal population (87, range 60-132), with a discrepancy between verbal (median 95, range 60-125) and performance (median 87, range 65-130) intelligence. Over 50% of the patients scored poorly on visual-motor integration, sustained attention, visual memory, planning, or motor speed. The other tested areas showed no differences between patients' and normal values. CONCLUSION: Neurocognitive diagnostics are indicated in cystinosis patients. Early recognition of specific deficits and supervision from special education services might reduce learning difficulties and improve school careers.

Effect of anionic fluidized ion exchange (FIX) pre-treatment on nanofiltration (NF) membrane fouling.

Anionic Fluidized Ion Exchange (FIX) is used to improve the performance of downstream Nanofiltration (NF). The research is divided in three parts: (i) NOM removal by FIX, (ii) the effect of FIX treatment on NF fouling and (iii) FIX treatment in relation to biological stability. Pre-treated anaerobic groundwater was (i) fed directly to a 4-inch membrane element and (ii) fed to another 4-inch membrane element after anionic FIX treatment. The operational parameters of the membrane set-up were monitored during 42 days, followed by a membrane autopsy study in which accumulated biological, organic and inorganic fouling was determined. Parallel to this experiment, two small ion exchange (IEX) resin and glass beads filled columns were operated to study the effect of FIX on the biomass concentration of the feed water. FIX operated satisfactory and selectively removed humic substances (>90%) and hydrophobic organic carbon (HOC) (>80%) from the feed water. Furthermore, iron was substantially removed (71%) which was explained by complexation with humic substances. Removal of NOM by FIX did not reduce membrane fouling problems; the Membrane Transport Coefficient (MTC) decreased and the Normalized Pressure Drop (NPD) increased more rapidly for the NF membrane after FIX compared to the membrane without FIX pre-treatment. NOM removal by FIX did not reduce adsorption of organic matter onto the downstream membrane element, since predominantly humic substances were removed which did not adsorb to the membrane surface. FIX treatment resulted in higher biomass densities (400%) and slightly less iron deposition (20%) onto the membrane surface. Fouling of the membrane element after FIX treatment was dominated by biofouling and fouling of the reference membrane element experienced more colloidal iron fouling compared to the membrane element after FIX, both resulting in an increase in NPD. The microbiological water quality deteriorated after anionic FIX treatment, as was observed by an increase in ATP content. Growth of biomass onto the IEX resins was observed which was caused by both IEX materials and feed water components, such as NOM fractions.

Jeune syndrome: description of 13 cases and a proposal for follow-up protocol.

Jeune syndrome (asphyxiating thoracic dystrophy, ATD) is a rare autosomal recessive skeletal dysplasia characterized by a small, narrow chest and variable limb shortness with a considerable neonatal mortality as a result of respiratory distress. Renal, hepatic, pancreatic and ocular complications may occur later in life. We describe 13 cases with ages ranging from 9 months to 22 years. Most patients experienced respiratory problems in the first years of their life, three died, one experienced renal complications, and one had hepatic problems. With age, the thoracic malformation tends to become less pronounced and the respiratory problems decrease. The prognosis of ATD seems better than described in literature and in our opinion this justifies long term intensive treatment in the first years. We also propose a follow-up protocol for patients with ATD.

Absence of antibody-dependent, complement-mediated lysis of feline infectious peritonitis virus-infected cells.

Cats infected with virulent feline coronavirus which causes feline infectious peritonitis (FIP) usually succumb to disease despite high antibody concentrations. One of the mechanisms that can help resolving infection is antibody-dependent, complement-mediated lysis (ADCML) of infected cells. ADCML consists of virus-specific antibodies that bind to cell surface expressed viral proteins which result in complement activation and cell lysis. The objective of this study was to determine the sensitivity of FIP-virus (FIPV) infected cells towards ADCML and to examine the role of the accessory proteins 3abc and 7ab in this process. ADCML assays, using FIPV strain 79-1146 and its deletion mutant strain Delta 3abc/Delta 7ab, were performed on: (i) CrFK cells that show surface-expressed viral antigens, (ii) monocytes without surface-expressed viral proteins due to retention and (iii) monocytes with surface-expressed viral proteins since the antibody-mediated internalization of these proteins was blocked. As expected, no ADCML was detected of the monocytes without surface-expressed viral antigens. Surprisingly, no lysis was observed in the CrFK cells and the monocytes that do show surface-expressed viral proteins, while controls showed that the ADCML assay was functional. These experiments proof that FIPV can employ another immune evasion strategy against ADCML (besides preventing surface expression): the inhibition of complement-mediated lysis. This new evasion strategy is not attributed to the group-specific proteins since lysis of cells infected with FIPV Delta 3abc/Delta 7ab was not detected.

Threshold concentration of easily assimilable organic carton in feedwater for biofouling of spiral-wound membranes.

One of the major impediments in the application of spiral-wound membranes in water treatment or desalination is clogging of the feed channel by biofouling which is induced by nutrients in the feedwater. Organic carbon is, under most conditions, limiting the microbial growth. The objective of this study is to assess the relationship between the concentration of an easily assimilable organic compound such as acetate in the feedwater and the pressure drop increase in the feed channel. For this purpose the membrane fouling simulator (MFS) was used as a model for the feed channel of a spiral-wound membrane. This MFS unit was supplied with drinking water enriched with acetate at concentrations ranging from 1 to 1000 microg C x L(-1). The pressure drop (PD) in the feed channel increased at all tested concentrations but not with the blank. The PD increase could be described by a first order process based on theoretical considerations concerning biofilm formation rate and porosity decline. The relationship between the first order fouling rate constant R(f) and the acetate concentration is described with a saturation function corresponding with the growth kinetics of bacteria. Under the applied conditions the maximum R(f) (0.555 d(-1)) was reached at 25 microg acetate-C x L(-1) and the half saturation constant k(f) was estimated at 15 microg acetate-C x L(-1). This value is higher than k(s) values for suspended bacteria grown on acetate, which is attributed to substrate limited growth conditions in the biofilm. The threshold concentration for biofouling of the feed channel is about 1 microg acetate-C x L(-1).